The treatment of the kinematic endpoint is implemented in the same way as in Ref. [1]} by shifting the relevant logarithms and adding power-suppressed terms to achieve a cumulative distribution that approaches one
at the kinematic endpoint and has a smooth derivative approaching zero. In
particular, we introduce the additional parameters \(p, x_L, v_\mathrm {max}\)  and
modify all logarithms by power-suppressed terms according to
\(\ln \mathopen {}\mathclose {\left(\frac{x_L}{v}\right)} \rightarrow \frac{1}{p} \ln \mathopen {}\mathclose {\left[\mathopen {}\mathclose {\left(\frac{x_L}{v}\right)}^p-\mathopen {}\mathclose {\left(\frac{x_L}{v_\mathrm {max}}\right)}^p+1\right]}=L\,.\) 
